Releasable bumper block



Aug. 7, 1962 Filed July 24, 1958 Tluz l- 1.. D. CASON ETAL 3,048,227

RELEASABLE; BUMPER BLOCK 3 Sheets-Sheet 1 Aug, 7, 1962 Filed July 24,1958 L. D. CASON ETAL RELEASABLE BUMPER BLOCK 3 Sheets-Sheet 2 D. CASONETAL 3,048,227

RELEASABLE BUMPER BLOCK Aug. 7, 1962 3 Sheets-Sheet 3 Filed July 24,1958 United States harem @fifire 3,048,227 Patented Aug. 7, 19623,048,227 RELEASABLE BUMPER BLOCK Lloyd D. Cason and Kennedy J. Dugas,Erath, La., as-

. signors to Texaco Inc a corporation of Delaware Filed July 24, 1958,Ser. No. 750,791 11 Claims. (Cl. 166114) This invention is generallyconcerned with a downhole tool for deep wells. More specifically, it isconcerned with a disconnectable tubing support. Such tubing support isapplicable for work-over operations in wells that have been completedwith reduced diameter tubing at the bottom of the string.

A procedure is known, which is employed in working over a permanentlycompleted well, i.e. a Well that has been cased and tubed, withoutpulling the tubing of the well. This known procedure avoids the use of awireline operated tail pipe for such work over operation.

The foregoing known procedure, briefly, involves cemen-ting-oif a givenproducing zone prior to re-perforating and commencing production anewfrom the same or a higher zone. In the course of such operation, it isnecessary to wash out the old producing zone that is to be cemented.This may be done by fluid circulation accompanied by lowering the tubingdown into the zone that is being washed. Following such washing the oldzone is cemented under pressure, which is known as squeeze cementing.The squeeze cementing operation involves applying cement to the zone,using forward circulation out through the bottom of the tubing. Afterthe cement slurry has been applied thus, excess cement is reversed outby reverse circulation, i.e. from the annulus into the tubing. Then somepressure is held on the cement while it is given time to set. To applythese pressures, the annulus is sealed around the tubing by employing aseal nipple on the tubing and locating it within a packer that has beenset in the casing above the zone being squeezed.

Since the pressures involved in the squeeze operation mentioned above,are quite high, the force tending to raise the seal nipple and tubing upout of the packer becomes quite substantial. For this reason it has beenfound difficult to carry out the squeeze cementing operation withoutloss of pressure (due to the forcing of the seal nipple or nipples, upout of the packer). It is not feasible to apply tubing weight on thestring, in order to counteract this upward force. This is because thestring is suspended from the surface, and to attempt this would meanthat the tubing string would be released and tend to be lowered, whichwould force the seal nipple out of the packer in a downward direction,and again create a loss of pressure by breaking the seal. The reasonthis is so is because of the length of the tubing string involved, whichis relatively so great that compression on the tubing from the lowerend, can create substantially large changes in the length thereof. Thusfor example, the seal nipple or nipples can be moved several feet upwardunder the force involved duringthe squeeze operation, without moving thetop of the tubing string at the well head, at all.

Consequently, it is an object of this invention to provide a method andapparatus for overcoming the above mentioned difficulties.

It is another object of this invention to teach a method of releasablylatching a bumper block to the tubing string, so that the tubing stringmay be lowered through the block (and a packer underneath) for carryingout desired operations.

Another object of this invention is to provide a bumper block which hasreleasable latching structure so that tubing may be unlatched fromdirect supporting contact therewith, andbe lowered through the block.Thereafter such tubing may be raised again and relatched into positivecontact with the bumper block.

Briefly the invention is concerned with a downhole releasable bumperblock, for use in at least partially supporting a tubing string on apacker. Such bumper block comprises a latching head adapted to beconnected to said tubing string, and a hollow cylindrical body member,having friction means exteriorly thereof for engaging the walls of saidhole. The bumper block also comprises a bowl assembly in said bodymember which includes means for releasably engaging the latching head.The said hole assembly and said latching head, are so constructed andarranged that said latching head may be lowered axially relative to saidbody member for any desired distance after unlatching, and may berelatched after raising the latching head back within said bowlassembly.

The invention may be also briefly described as a method that isapplicable in a permanent type well completion. Such completion beingone that has a pre-determined length of reduced'diameter tubing at thebottom of the tubing string in said well. The method is one that isinvolved in a work-over procedure. The work-over procedure involving alowering of said tubing string, relative to a packer located adjacent tosaid reduced diameter tubing. The method includes the steps ofunlatching said tubing from a hollow cylindrical body member adapted torest on said packer, and lowering said tubing through said packer andbody member to carry out circulation of fluid through said tubing, Alsothe step of raising and relatching said tubing to said body member, andalso releasing suificient of the weight of said tubing string towithstand the pressure involved in a squeezing operation.

The foregoing and other objects and benefits of this invention, are setforth in the detailed description that follows, and are illustrated inthe drawings, in which:

FIG. 1 is an elevation assembly partly in cross section, showing thebumper block in place, resting on a packer that is schematically shownin cross section, and with a tubing string shown passing through thebumper block and packer;

FIG. 2 is an enlarged fragmentary elevation, largely shown inlongitudinal cross-section along the line 22 of FIG. 1, illustrating theelements of the bumper block according to a preferred embodiment of theinvention;

FIG. 3 is an enlarged detail showing of certain of the elements that goto make up the upper portion of the bumper block;

FIG. 4 is an enlarged detail elevation view showing the coil spring thatis employed within the bowl assembly of the bumper block;

FIG. 5 is an enlarged detail elevation partly broken away incross-section and illustrating a spring guide on which the bottom of thecoil spring shown in FIG. 4, rests;

FIG. 6 is an enlarged detail elevation, partially broken away in crosssection, illustrating the expanding thread segments that have the loadbearing female threads on the inner periphery thereof;

FIG. 7 is another enlarged detail elevation, partially broken away'incross-section, illustrating the stabilizer ring, that is located beneaththe expanding-thread seg ments;

FIG. 8 is an enlarged detail elevation partially broken away incross-section, illustrating the latching head that is adapted to beconnected into the tubing string; 7

FIG, 9 is an enlarged fragmentary detail elevation of the lower pontionof the bumper block at the bowl assembly portion thereof. This showingis broken away in crosssection to show the internal structure includingan axially extending key that co operates with the thread segmentsillustrated in FIG. 6;

FIG. 10 is a transverse cross-section view, taken along 3 the lines -10of FIG. 2 looking in the direction of the arrows;

FIG. 11 is another transverse cross-section view taken along the lines1111 of FIG. 2 looking in the direction of the arrows; and

FIG. 12 is a fragmentary cross-sectional view, showing a modified formfor the elements of the bumper block that provide frictional engagementwith the walls of the hole.

Referring to FIG. 1, it is pointed out that there is illustrated afragmentary portion of a deep well 21, which has been drilled into theearth to reach under-lying strata such as formations 22 and 23illustrated. Such a deep well is ordinarily lined with a casing 24,although if the formations are sufliciently hard a casing might notalways be required.

Throughout this description, wherever the walls of the hole are referredto, it is contemplated that such walls include the casing, if the holeis cased, or the walls of the hole formed by the formation, if the holeis uncased.

There is a conventional type of production packer 25, schematicallyillustrated. This packer 25 has been expanded to provide a tight highpressure seal with the casing 24. There is shown situated within packer25 a conventional seal nipple that is connected into a reduced diametertubing string 31, which passes through the bumper block 32 that is shownresting upon the top edge of the packer 25.

The type of operation in which this invention is employed, has beenbriefly indicated above. Such operation (when applied to the apparatusshown in FIG. 1) includes a lowering of the tubing string 31 through thebumper block 32 and the packer 25, after the tubing string has beenunlatched from the bump r block internally thereof. It will beappreciated that the reduced diameter tubing string 31 is attached atthe lower end of the normal sized, full diameter tubing string (notshown) in the well. Such reduced diameter tubing string will have beenattached to the main tubing string as the well is completed, in orderthat the procedures for re-working the well may be carried out, withoutremoving the tubing from the well.

The operation involves a lowering of the reduced diameter tubing string31, sufliciently to move the seal nipple 30 out of contact with thepacker 25 in order to provide free passage for fluids from the annulusabove the packer 25 to the annulus beneath the packer. Thus acirculation of fluids may be carried out under such circumstances; andany accumulation of sand or debris may be washed clear, prior to asqueeze cementing operation. A squeeze cementing operation involvesapplying pressure to the cement following injection thereof through thetubing 31. And, in order to apply and maintain such pressure, the tubingstring 31 is raised until the seal nipple 30 again rests within thepacker 25 (in the manner illustrated in FIG. 1). When this conditionexists, and the tubing string 31 has been re-latched into positivecontact with the bumper block 32, squeezing pressures may be applied tothe cement, and will be maintained without forcing the seal nipple 30 upout of the packer 2 5. This is so because tubing-string-weight may beapplied to the bumper block 32, since the string 31 is now latched intopositive connection with the bumper block 32.

Ordinarily the full weight of the tubing string 31 will not be applied,for fear of causing a buckling in the tubing string. However, by reasonof the bumper block being attached to the string 31 with a positiveconnection, sufficient tubing weight may be applied to insure that thesqueeze pressure will not be able to lift the seal nipple 30 up out ofthe packer. The excess of such tubing weight will be carried in asupporting manner by the upper edge of the packer 25, upon which thebumper block 32 rests. Referring to FIGS. 2ll, the details of thestructure of the bumper block 32 will be described.

There is a latching head 35 (FIG. 2 and FIG. 8) that may be called atubing support or latching nipple and is connected into the tubingstring 31, as indicated by the broken line showing of the tubing stringin FIG. 2. Such connection with the string 31, by the latching head ortubing support 35, is made by means of upper internal pipe threads 36for the upper portion of the tubing string, and lower pipe threads 37for the tubing string connected below the tubing support or latchinghead 35. On the outer surface at the upper end of the tubing support 35,when viewed as shown in the drawings, there is a set of male buttresstype load bearing threads 38. At the other end of the latching head ortubing support 35, there is an enlarged cylindrical collar section 39.

The structure of the bumper block proper (that acts to support thelatching head or tubing support 35) includes a hollow cylindrical bodyportion, or body member 43 (FIG. 2). This is made up of two separableportions, including an upper sleeve-like unit 44 (FIGS. 2 and 3) thathas a relatively short, thick walled hollow cylinder 45 surrounding partof the lower end thereof. Cylinder 45 is welded to a sleeve 47, at theupper edge of the cylinder 45 as indicated at reference number 46.

The lower portion of the body member 43, includes a lowereylinder-and-sleeve unit 48 (FIGS. 2 and 9) that includes an outersleeve 56 that has internal threads 51 at one end thereof, adapted formeshing with threads 53 on the outside lower portion of the hollowcylinder 45 of the upper unit 44. The lower end of the sleeve 50surrounds, and is securely attached to, the upper end of a lowercylindrical portion 54. This attachment may be accomplished in anyfeasible manner, such as by means of a weld 52 illustrated.

Attached .to the thick walled portion of cylinder 54, there is aplurality of hole-wall-engaging bowed springs 56. Springs 56 areattached to the cylinder 54 in any feasible manner, such as by employingcap bolts 57, as illustrated. At the other end of the springs 56 thereis a supporting ring 58, to which the bowed springs 56 are attached bymeans of flush head bolts 59, as illustrated.

Generally within the sleeve 50, there are located the elements of a bowlassembly. These bowl assembly elements include the main element of thelatching structure, viz. a plurality of frusto-conical annularlysituated segments 63 (FIGS. 2 and 6). These segments 63 have on theinner peripheral surface thereof, female buttress type threads 64, whichare cut for engagement with the male buttress threads 38 on the tubingsupport or latching head 35. Segments 63 rest within a frusto-conicallywalled chamber 65, that is formed by the widening portion of the upperextremity of cylinder 54, where it extends within the outer sleeve 50.Underneath the segments 63 in the bowl assembly, there is a stabilizerring 66 (FIGS. 2 and 7), which rests upon a shoulder 67 formed in thecylinder 54. On top of the segments 63 there is a spring-guide ring 70(FIGS. 2 and 5). Guide ring 70 supports a coil spring 71 (FIGS. 2 and4). The other end of spring 71 rests against the lower edge of the uppercylinder 45.

It is pointed out that the threads 51 and 53 which join the upper andlower portions of the body member 43 together, are a tight fit so thatwhen assembled, the entire bumper block 32 acts as a unitary whole.

Referring to FIGS. 10 and 11 it will be observed that the segments 63are so proportioned as to be in contact with one another at the edgesthereof, with the exception of a space 74 that is formed betweensegments 63a and 6312. This space 74 is provided to accommodate a key 75that is welded to the upper extension of the cylinder 54, above theshoulder 67. Key 75 thus prevents relative rotation between thecylinder-and-sleeve unit 48 and the segments 63. However, the segments63 are free to move longitudinally (i.e. parallel to the axis of thebumper block 32) against the spring pressure of spring 71. Suchlongitudinal axial movement of the segments 63,

aoaaaav Operation Referring especially to FIGS. 1 and 2, the operationmay be explained in accordance with the following. With the elements inthe relative positions illustrated, the tubing string 31 is connected tothe tubing support or latching head 35, and the tubing string istherefore latched to the bumper block 32. When it isdesired to unlatchthe tubing string 31, it will be raised to lift the bumper block 32 offof the packer 25, so that the bumper block 32 is supported by means ofthe buttress threads 38 and 64 in addition to the large collar section39 on the latching head 35. Now when the tubing string 31 is rotated,the latching head 35 will of course rotate therewith. However, by reasonof the bowed springs 56, the bumper block 32 and particularly thecylinder 54 thereof, will tend to remain stationary by reason of thedrag friction between bowed springs 56 and the casing 24 of the well 21.Thus, by rotating the latching head 35 by means of the tubing string 31,in the proper direction, the body member '43 of the bumper block willbecome disconnected from the string on account of unscrewing the threadconnection at the loose fitting buttress threads 38 and 64.

Ifthe tubing string 31 is held vertically stationary while it isrotated, body member 43 will climb upward as the threads are unscrewedfrom one another. After the buttress threads have become completelyunscrewed from one another the tubing support or latching head 35 may belowered along with the tubing string 31, as far as desired, dependingupon the length of the reduced diameter tubing that has been installedand the depth to the bottom of the hole. When the tubing string 31 isthus lowered, carrying tubing support 35rtherewith, the bottom edge ofcylinder 54 of the bumper block 32, will contact the packer 25 once moreand remain there as the tubing is lowered therethrough. Lowering of thetubing will, of course, lower the seal nipple 30 out of the packer 25and permit flow of fluids through the annulus past the packer.

After the completion of a washing operation, or other steps that may be.taken while the tubing string is unlatched from the bumper block 32, thetubing string may be again raised to bring the latching head 35 intocontact once more with the threads 64 of the segments 63. Following suchcontact, the tubing string will be raised sufficiently to lift .the bodymember 43 for a distance above the packer 25 that is s'ufiicient toallow for the downward movement of the body member 43, as the relatchingoperation takes place. Such re-latching is accomplished by merelyreversing the earlier steps, i.e. by-

rotating the tubing string 31, and the latching head 35 therewith, inthe proper direction to screw the loose fitting buttress threads'oflatching head 35 and of segments '63, back together.

As explained above, the body member 43 will not rotate, freely with thelatching head 35 as it is rotated, because of the friction drag effectat the walls of the hole that is created by the bowed springs 56.

In order to be sure that the threads 64, of all of the segments 63, areproperly meshed with the threads 38 of the latching head 35, it isadvisable to rotate the latching head 35 for a full revolution in theopposite (or unscrewing) direction prior to the rotation in the forward,or screwing direction, when proceeding to relatch the string to thebumper block.

It will be noted that, by reason of the expanding thread structure ofsegments 63 and the tapering chamber walls 65, latching head 35 may bere-latched to the body member 43 without any rotation thereof. In otherwords,

the mere straight lifting action of latching head or tubing support 35will cause the segments 63 to rise and spread, so that the meshing ofthe threads on latching head or tubing support 35 may be accomplishedbythe ratcheting action of the buttress threads over one another.However, in any event, it is most advisable to rotate the tubing string31 for a full revolution in the backward or unscrewing direction priorto a release of the tubing string Weight for support thereof on thepacker 25. Such reverse rotation will make sure that the threads of allof the segments 63 are properly meshed at the same level without anycross threading.

Method Steps It will be observed that the apparatus which has beendescribed may be employed to carry out a method that is applicable tothe procedure that is involved in a permanent type Well completionoperation. volved in the working over of the well following theaforementioned permanent type completion. The procedure has beendescribed in general terms above.

It will be clear that in such a procedure the apparatus may be employedto carry out the following steps, including unlatching the tubing fromthe hollow cylindrical body member that is adapted to rest on a packer,lowering said tubing through the packer and body member in order to beable to carry out fluid circulation opera tions where fiuid iscirculated either down the annulus between the casing and the tubing andup inside of the tubing or the reverse. In addition, the procedure mayinclude the additional steps of raising and re-latching the tubingstring to the body member, as well as releasing sufficient of the weightof the tubing string so as to provide downward force to withstand thepressure involved in a squeezing operation when the tubing string islatched in position (the seal nipple is located within the packer).

Modified Friction Springs FIG. 12 illustrates a different hole-Wallengaging friction drag means, to replace the bowed springs 56 of themodification described in the previous figures.

Referring to FIG. 12 it will be observed that there is a plurality offriction blocks at} that are mounted partially recessed in the lowercylindrical portion 54a of the body member. These friction blocks 30 aredesigned to provide more frictional force against the walls of the holethan would be applied with the other style friction wall engagingsprings 56. Thus the friction blocks are spring biased radially outwardinto extended positions as illustrated in FIG. 12, by means of a doubleset of coil springs 81 and 82 located in each of a set of three recesses 85, 86 and 87, in turn located in each of the friction blocks 80.Each of the friction blocks 80 is held in position in an elongatedrecess 90 in the wall of the cylinder 54a. Each block 80 is held inposition in its recess 90, against the force of the coil springs 81 and82,

.by means ofa pair of flat headed machine screws 91 and 92. The heads ofthese screws 91 and 92 overlap the edge of the recess 90, and makecontact with the block 80 in notches 93 and 94 respectively.

All of the other elements of the bumper block, remain the same asalready illustrated and described above.

It is pointed-out that while FIG. 12 illustrates only two frictionblocks 80 it will be clear that more than two (preferably four) could beemployed if desired.

While certain embodiments of the invention have been illustrated anddescribed in considerable detail in accordance with the aplicablestatues, this is not to be taken as in any Way limiting the invention,but merely as being descriptive thereof.

What is claimed as the invention is:

1. For use in a well bore having an internal packer fixedly mountedtherein, a tubing string adapted to pass freely through the packer, andsaid tubing string being provided with a seal nipple engageable with thepacker in sealing relationship; means for selectively holding the sealnipple in the packer comprising a bumper block about the tubing stringabove the packer and adapted to rest thereon, a tubing support connectedinto said tubing Such operation is instring, and means controlled fromthe well head for latching said tubing support to said bumper block whensaid seal nipple is engaged in said packer to hold said seal nippletherein, said latching means being selectively releasable to permitdownward movement of the tubing string in the well.

2. In the combination according to claim 1, the said latching meansincluding load bearing means on said tubing support, and complementarymeans on said bumper block for meshing with said load bearing means.

3. The invention according to claim 2 further including friction meanson said bumper block for restraining the bumper block against rotationin the well.

4. The invention according to claim 3 wherein said load bearing meanscomprises machine threads.

5. The invention according to claim 4 wherein said complementary meanscomprises a plurality of segments having threads on the inner surfacesthereof matching with said machine threads.

6. The invention according to claim 5 wherein said plurality of segmentsinclude a tapered outer circumferential configuration to allow fordiametrical expansion thereof.

7. The invention according to claim 6 further including a bowl assemblyintegral with said bumper block for housing said segments, and biasmeans for urging the segments into diametrically contracted position.

8. A disconnectable tubing support assembly for use in deep welloperations, comprising in combination a tubing support adapted to beconnected into a tubing string, a bumper block freely embracing saidtubing support for permitting free downward movement of said tubingsupport relative to said bumper block when disconnected therefrom, saidbumper block including a frusto-conically Walled chamber, machinethreads on said tubing support for latching and unlatching with saidbumper block, and a plurality of segments having a tapered outercircumferential configuration to allow for diametrical expansion thereofand being located within said chamber and having threads on the innersurfaces thereof matching with said machine threads, said bumper blockbeing so constructed and arranged that by surface manipulation of saidtubing string said tubing support may be connected and disconnectedrelative thereto as desired.

9. The invention according to claim 8 further including bias means forurging the segments into diametrically contracted position.

=10. A down hole releasable bumper block for use in at least partiallysupporting the weight of a tubing string on a packer, comprising alatching nipple adapted to be connected to said tubing string, loadbearing threads on said latching nipple for carrying said tubing stringload, a hollow body member adapted to receive said tubing stringextending therethrough, said body member having friction meansexteriorly thereof for engaging the walls of said hole, a bowl assemblyin said body member, said assembly comprising a plurality of taperedthread segments adapted for threaded cooperation with said load bearingthreads, a tapered chamber for receiving said segments, and key meansfor preventing relative rotation between said segments and said bodymember, said tapered chamber having an axial dimension greater than thecorresponding axial dimension of said segments to provide for radialexpansion of said tapered thread segments, spring bias means for urgingsaid segments axially into radially contracted position within saidtapered chamber, said tapered chamber being relatively situated in saidbody with the minimum diameter of the taper at the lower end when saidbumper block is in place above said packer.

11. A down hole releasable bumper block for use in at least partiallysupporting the weight of a tubing string on a packer, comprising ahollow body member, hole wall engaging friction drag means mountedexteriorly on said body member and having means for biasing said dragmeans radially outward against the walls of said hole, a bowl assemblyon the interior of said body member, said bowl assembly comprising afrusto-conical walled chamber with the minimum diameter at the endnearest said packer, a plurality of frusto-conical annular segmentswithin said chamber having load bearing female threads on the innersurfaces thereof and including a predetermined circumferential spacebetween two of the segments, a key attached to said body member andlocated in said circumferential space for insuring against rotation ofsaid segments relative to said-body member, a spring for urging saidsegments toward the minimum diameter end of said chamber, a latchingnipple adapted for connection into said tubing string, said latchingnipple having load bearing male threads thereon for engagement with saidfemale threads on said segments, the outside diameter of said malethreads being less than the inside diameter of said body member belowsaid bowl assembly, so that said tubing string may be unlatched andlowered out of said body member for reversing operations and relatchedthereafter for squeeze operations and the like.

References Cited in the file of this patent UNITED STATES PATENTS1,824,283 Marr Sept. 22, 1931 2,156,939 Fulkerson May 2, 1939 2,187,480Baker Ian. 16, 1940 2,187,483 Baker Jan. 16, 1940 2,644,524 Baker July7, 1953 2,687,774 Hodges Aug. 31, 1954 2,737,248 Baker Mar. 6, 19562,751,009 Wooddy June 19, 1956 2,893,492 Brown July 7, 1959

